<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>css处理</title>
    <style>
        div{
            width: 100px;
            height: 100px;
            background-color: red;
        }
        .c1{
            width: 200px;
            height: 200px;
            background-color: green;
            border-radius: 50%;
        }
    </style>
    <script type="text/javascript" src="../../js/jquery-3.4.1.min.js"></script>
    <script>
        $(function (){
            $("div").mouseover(function(){
                // className
                // $(this).addClass("c1");
                // 行内式,style
                // css(样式名):获取指定样式的值
                // css(样式名,样式值):设置css样式
                $(this).css("width","200px")
                $(this).css("height","200px")
                $(this).css("background-color","green")
                $(this).css("border-radius","50%")
            });
            $("div").mouseout(function(){
                // $(this).removeClass("c1");
                $(this).css("width","100px")
                $(this).css("height","100px")
                $(this).css("background-color","red")
                $(this).css("border-radius","0%")
            });
        })
    </script>
</head>
<body>
<div></div>
</body>
</html>